Orthopedic casts for use in treating bone fractures or other conditions requiring immobilization of a body member are generally formed from a sheet of fabric or scrim material coated or impregnated with a substance that hardens into a rigid structure after the sheet has been wrapped around the body member.
Many orthopedic casts now commonly used are comprised of a backing impregnated with a water-curable isocyanate-functional prepolymer. The backing can be knitted, woven, or nonwoven scrim comprised of natural, polymeric, or glass fibers. The preferred scrim materials are knitted fiberglass scrims. These casts when cured have a higher strength to weight ratio than plaster-of-paris, are more resistant to water and provide good radiolucency.
U.S. Pat. No. 4,411,262 (von Bonin), U.S. Pat. No. 4,502,479 (Garwood), and U.S. Pat. No. 4,667,661 (Scholz et al.) disclose water-curable isocyanate-functional prepolymers useful in orthopedic bandages. The prepolymer typically includes a tertiary amine catalyst in an amount selected to optimize the "set" time. After the resin-impregnated scrim has been immersed in water, sufficient "working time", e.g., 3 to 5 minutes, should be provided in which the wrapping is accomplished and the cast is manually molded into a desired shape. However, after the cast is shaped, the resin should continue to harden and rapidly build strength, typically in 15-30 minutes, into a rigid, high-strength, weight-bearing cast.
U.S. Pat. No. 4,376,438 (Straube et al.) discloses an orthopedic casting material wherein the tertiary amine catalyst is incorporated into the backbone of the polymer portion of the isocyanate-functional prepolymer. No separate catalyst is required.
U.S. Pat. No. 4,502,479 (Garwood et al.) discloses the use of tertiary alkanolamines, e.g., dimethylethanolamine, as catalysts in the curing of a water-curable isocyanate-functional prepolymer. At concentrations which do not adversely affect shelf stability, these catalysts do not cure as fast as desired by many experienced cast appliers.
U.S. Pat. No. 4,433,680 (Yoon) discloses the use of 2,2'-dimorpholinyldiethyl ether (DMDEE) as a catalyst in the cure of a water-curable isocyanate-functional prepolymer on an open-weave fibrous substrate to form an orthopedic bandage.
U.S. Pat. No. 4,705,840 (Buckanin) discloses the use of 2,2'-dimorpholinyldialkyl ethers substituted on one of the carbon atoms alpha to the central ether oxygen atom as catalysts in the curing of water-curable isocyanate-functional prepolymers.
Various compounds of Formula I below are known. For example, 2-(dialkylamino)ethyl 1-alkylprolinates are described in West German Pat. No. DE 1,933,411 (Likhosherstov et al., abstracted at Chemical Abstracts 76:153583m), Khim.-Farm.Zh. 1967, 1, 26 (Lebedeva et al., abstracted at Chemical Abstracts 67:82022d), and Khim.-Farm.Zh. 1973, 7, 10 (Likhosherstov et al., abstracted at Chemical Abstracts 79:53122d) as low toxicity ganglioplegic agents. Similarly, 2-(dialkylamino)ethyl 1-methylpipecolinates are described in Soviet Union Pat. No. 278027 (Likhosherstov et al., abstracted at Chemical Abstracts 74:53512c) as pharmaceutical agents. 2-(1-Piperidinyl)ethyl and 2-(4-morpholinyl)ethyl 4-morpholineacetates and 1-piperidineacetates are described in Acta. Pol. Pharm. 1979, 36 1 (Wolinski et al., abstracted at Chemical abstracts 91:123691n) as anticholinergic agents, and various aminoalkyl esters of piperidino- and morpholino- acetic acid are described in Acta. Pol. Pharm. 1980, 37, 397 (Wolinski et al., abstracted at Chemical Abstracts 95:80069d) and Pol. J Pharmacol. Pharm. 1978, 30, 497 (Faff et al., abstracted at Chemical Abstracts 91:32648n). 2-(Diethylamino)ethyl dimethylaminoacetate is described in Farm.Zh. (Kiev) 1990, 1, 38 (Grinevich et al., abstracted at Chemical Abstracts 114:42025q) as having significant inotropic activity. Also, 2-(diethylamino)ethyl N,N-dimethylglycinate is described in Khim.-Farm.Zh. 1983, 17, 916 (Razina et al., abstracted at Chemical Abstracts 99:169415u) and said to possess analgesic activity.